W57A Apoflavodoxin from Anabaena

Experimental Data Snapshot

  • Resolution: 2.05 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.169 

wwPDB Validation   3D Report Full Report

This is version 1.5 of the entry. See complete history


Dissecting the Energetics of the Apoflavodoxin-Fmn Complex

Lostao, A.El-Harrous, M.Daoudi, F.Romero, A.Parody-Morreale, A.Sancho, J.

(2000) J Biol Chem 275: 9518

  • DOI: https://doi.org/10.1074/jbc.275.13.9518
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Many flavoproteins are non-covalent complexes between FMN and an apoprotein. To understand better the stability of flavoproteins, we have studied the energetics of the complex between FMN and the apoflavodoxin from Anabaena PCC 7119 by a combination of site-directed mutagenesis, titration calorimetry, equilibrium binding constant determinations, and x-ray crystallography. Comparison of the strength of the wild type and mutant apoflavodoxin-FMN complexes and that of the complexes between wild type apoflavodoxin and shortened FMN analogues (riboflavin and lumiflavin) allows the dissection of the binding energy into contributions associated with the different parts of the FMN molecule. The estimated contribution of the phosphate is greatest, at 7 kcal mol(-1); that of the isoalloxazine is of around 5-6 kcal mol(-1) (mainly due to interaction with Trp-57 and Tyr-94 in the apoprotein) and the ribityl contributes least: around 1 kcal mol(-1). The stabilization of the complex is both enthalpic and entropic although the enthalpy contribution is dominant. Both the phosphate and the isoalloxazine significantly contribute to the enthalpy of binding. The ionic strength does not have a large effect on the stability of the FMN complex because, although it weakens the phosphate interactions, it strengthens the isoalloxazine-protein hydrophobic interactions. Phosphate up to 100 mM does not affect the strength of the riboflavin complex, which suggests the isoalloxazine and phosphate binding sites may be independent in terms of binding energy. Interestingly, we find crystallographic evidence of flexibility in one of the loops (57-62) involved in isoalloxazine binding.

  • Organizational Affiliation

    Departamento de Bioquímica y Biología Molecular y Celular, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C, D
169Nostoc sp. PCC 7119Mutation(s): 1 
Gene Names: isiB
Find proteins for P0A3E0 (Nostoc sp. (strain ATCC 29151 / PCC 7119))
Explore P0A3E0 
Go to UniProtKB:  P0A3E0
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A3E0
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.05 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.169 
  • R-Value Observed: 0.169 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 74.14α = 90
b = 55.52β = 107.04
c = 75.18γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-04-10
    Type: Initial release
  • Version 1.1: 2011-05-07
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-07-05
    Changes: Data collection
  • Version 1.4: 2019-09-25
    Changes: Data collection, Database references, Other, Source and taxonomy, Structure summary
  • Version 1.5: 2023-12-06
    Changes: Advisory, Data collection, Database references, Derived calculations, Refinement description